Insulated flowpath assembly

ABSTRACT

A flowpath assembly has a first conduit defining a flowpath radially inward, and a second conduit spaced radially outward from the first conduit. A void defined between the first and second conduits contains an insulating material that may have a greater porosity than the first and second conduits. The assembly may be additive manufactured generally as one unitary piece with the raw material of the conduits being melted and solidified on a slice-by-slice basis and the insulating material being selectively bypassed by an energy gun of an additive manufacturing system.

This application claims priority to U.S. Patent Appln. No. 62/020,723filed Jul. 3, 2014.

BACKGROUND

The present disclosure relates to a flowpath assembly, and moreparticularly to an insulated flowpath assembly.

Manufacturing of flowpath assemblies such as those containing conduitswithin conduits (or concentrically located conduits), as one example,require the manufacture of several individual parts, then assembly tocreate the final product. In some examples, air within an annular voiddefined between the two concentrically located conduits acts as athermal insulator for fluid that may be flowing through the innerconduit. Sealing of this void (i.e. complete encapsulation) to enhancethe thermal properties of the surrounding air is difficult from amanufacturing perspective and not typically accomplished, and if suchwere accomplished, it would require yet further parts thus limitingfeasibility.

There exist needs in various industries to reduce the number ofmanufactured parts for conduit or conduit-like assemblies, therebyproviding more robust and simpler designs requiring less maintenance,reducing manufacturing time and costs, improving thermal barriercharacteristics, and/or reducing thermal conduction paths between innerand outer conduits of the assemblies, amongst others.

SUMMARY

A flowpath assembly according to one, non-limiting, embodiment of thepresent disclosure includes a first conduit defining a flowpath radiallyinward and extending along a centerline; a second conduit spacedradially outward from the first conduit with a void defined by andradially between the first and second conduits; and an insulatingmaterial disposed in the void.

Additionally to the foregoing embodiment, the void is sealed and at anegative atmospheric pressure.

In the alternative or additionally thereto, in the foregoing embodiment,the first and second conduits are additive manufactured simultaneously.

In the alternative or additionally thereto, in the foregoing embodiment,the insulating material is a powder deposited during the simultaneousadditive manufacturing of the first and second conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the first and second conduits are one unitary piece.

In the alternative or additionally thereto, in the foregoing embodiment,the assembly includes a third conduit co-extending with the firstconduit and spaced radially inward from the second conduit.

In the alternative or additionally thereto, in the foregoing embodiment,the assembly includes a support structure located in the void andengaged between the first and second conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the first and second conduits and the support structure are additivemanufactured as one unitary piece.

In the alternative or additionally thereto, in the foregoing embodiment,the insulating material has a greater porosity than the conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the assembly is part of a fuel injector for a gas turbine engine.

In the alternative or additionally thereto, in the foregoing embodiment,the first conduit is substantially concentric to the second conduit.

A flowpath assembly according to another, non-limiting, embodimentincludes a first conduit for flowing a fluid; a second conduitsurrounding and spaced radially outward from the first conduit with aninsulating void defined between the first and second conduits; a looselypacked material in the void; and wherein the flowpath assembly isadditive manufactured as one unitary piece.

Additionally to the foregoing embodiment, the material has insulatingproperties and is deposited during additive manufacturing of the firstand second conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the assembly includes a support structure in the void and including aplurality of pylons each engaged to and extending between the first andsecond conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the insulating material and the support structure have the same materialcomposition.

A method of manufacturing a flowpath assembly according to another,non-limiting, embodiment includes the steps of electronically modelingthe flowpath assembly having a first conduit co-extending and surroundedby a second conduit; additive manufacturing the first conduit; additivemanufacturing the second conduit generally simultaneously tomanufacturing of the first conduit; and depositing an insulatingmaterial generally during manufacturing of the first and secondconduits.

Additionally to the foregoing embodiment, the additive manufacturing ofthe first and second conduits and the depositing of the insulatingmaterial all include depositing of a powder.

In the alternative or additionally thereto, in the foregoing embodiment,the method includes the step of additive manufacturing a supportstructure engaged between the first and second conduits and generallyduring the manufacturing of the first and second conduits.

In the alternative or additionally thereto, in the foregoing embodiment,the support structure and the insulating material are made of the samematerial composition.

In the alternative or additionally thereto, in the foregoing embodiment,the flowpath assembly is modeled into a plurality of slices each slicehaving a portion of the first conduit, the second conduit and theinsulating material, and a first slice of the plurality of slices ismanufactured in-part through melting and solidification beforeproceeding to the manufacture of a next successive slice of theplurality of slices, and the insulating material is not melted.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in-light of the following description and the accompanyingdrawings. It should be understood; however, that the followingdescription and figures are intended to be exemplary in nature andnon-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiments. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a cross section of a combustor of a gas turbine engineillustrating a fuel injector as an example of a flowpath assembly of thepresent disclosure;

FIG. 2 is a cross section of the flowpath assembly;

FIG. 3 is a partial cross section of a second embodiment of a flowpathassembly;

FIG. 4 is a partial cross section of a third embodiment of a flowpathassembly;

FIG. 5 is a partial cross section of a fourth embodiment of a flowpathassembly;

FIG. 6 is a schematic of an additive manufacturing system used tomanufacture the flowpath assembly; and

FIG. 7 is a flow chart of a method of manufacturing the flowpathassembly.

DETAILED DESCRIPTION

FIG. 1 illustrates a fuel injector for a gas turbine engine as one,non-limiting, example of a flowpath assembly 20. The fuel injector 20 ispart of a combustor 22 that may be annular in shape and concentricallydisposed to an engine axis A. The combustor 22 may further include abulkhead assembly 24, an outer wall 26, an inner wall 28, and a diffusercase module 34. The outer and inner walls 26, 28 project axially in adownstream direction from the bulkhead assembly 24, and radially definean annular combustion chamber 30 therebetween. An annular cooling plenum32 is generally defined radially between the outer diffuser case module34 and a diffuser inner case 36 of the engine. The bulkhead assembly 24and walls 26, 28 are located in the cooling plenum 32 immediatelydownstream from a compressor section 38, and upstream from a turbinesection 40 of the engine.

The annular bulkhead assembly 24 may extend radially between and issecured to the forward most ends of the walls 26, 28. Assembly 24generally includes an annular hood 42, a wall or heat shield 44 thatdefines the axial upstream end of the combustion chamber 30, and aplurality of swirlers 46 (one shown) spaced circumferentially aboutengine axis A and generally projecting or communicating through the wall44. A plurality of circumferentially distributed hood ports 48accommodate a respective plurality of the fuel injectors 20 as well asdirect compressed air C into the forward end of the combustion chamber30 through the associated swirler 46.

The bulkhead assembly 24 introduces core combustion air into theupstream end of the combustion chamber 30 while dilution and cooling airis introduced into the combustion chamber 30 through the walls 26, 28and from the plenum 32. The plurality of fuel injectors 20 andrespective swirlers 46 facilitate the generation of a blended fuel-airmixture that supports combustion in the combustion chamber 30.

Each fuel injector 20 may receive fuel from at least one fuel manifold50 generally located radially outward of the case module 34. Theelongated fuel injector 20 may substantially extend longitudinally alonga centerline 52 and in a radial inward direction with respect to theengine axis A, through the case module 34 and into the plenum 32. Thecenterline 52 and thus the injector 20 then bends (i.e. see bend 54) andprojects in an axial downstream direction, extending through the hoodport 48 and into the swirler 46 where fuel is then dispensed andatomized from the injector 20.

Referring to FIG. 2, the flowpath assembly 20 (i.e. a simplified fuelinjector in the present example) may have a first or inner conduit 56co-extending with and surrounded by (e.g. concentrically located) to asecond or outer conduit 58. The outer conduit 58 may be spaced radiallyoutward from the inner conduit 56 thereby defining a substantiallyannular void 60, therebetween. Void 60 is generally filled with aloosely packed or granular material 61 that may have insulatingproperties, and the void may further be generally sealed (i.e.completely encapsulated) from the plenum 32 and/or surroundingenvironment to further enhance thermal insulation of fluid (see arrow62) flowing through the inner conduit 56. To further enhance the thermalinsulating properties, the void 60 may be under a negative atmosphericpressure and may further contain an inert gas such as nitrogen (N₂),Argon or any other gas compatible with the material composition of thesurrounding structures and material 61. Although liquid fuel in thepresent example, it is contemplated and understood that the fluid 62 mayalso be a gas, liquid such as oil and water, or even a solid material(e.g. powder) capable of flow. It is further understood that the term“conduit” also refers to tubes, casings, pipes and other structurescapable of fluid flow and/or encasement of the insulating material 61.

Such fuel injectors 20 flowing liquid fuel and operating in hotenvironments like the plenum 32 where temperatures may exceed 1,700degrees Fahrenheit (927 degrees Celsius) are susceptible to fuelvarnishing and coking due to high temperatures of more traditional fluidbearing conduit(s). This coking can lead to decreased flow capacity ofthe injector and decreased quality of fuel delivery. To manage thetemperature of the conduit 56 and thus the fluid or fuel 62 and preventcoking, the void 60 is employed to break the thermal conduction pathfrom the hot external environment to the inner conduit 56. It is furthercontemplated and understood that other portions of a fuel deliverysystem of the gas turbine engine may employ the same type of assembly20. For instance, the fuel manifold 50 may be susceptible to similarcoking issues leading to unintentional mal-distribution of fuel in thesystem, and thus benefit from the same means of insulating a conduitbearing fluid flow.

The inner and outer conduits 56, 58 may each have at least onerespective bend 64, 66 that generally corresponds with the bend(s) 54 ofthe centerline 52 and such that the void 60 is generally maintained(i.e. spacing between conduits). The bends 64, 66 may be such wherelongitudinal insertion of the inner conduit 56 into the outer conduit 58(and if the conduits were separate pieces) is not possible. With suchfitting difficulties, additive manufacturing the conduits 56, 58generally together and/or simultaneously is advantageous. As an exampleof such insertion difficulties that the additive manufacturing processresolves, the outer conduit 58 may be lacking any line-of-site throughthe conduit and the inner conduit 56 is too large to freely fitcompletely into the outer conduit 58. More specifically, the outerconduit 58 may have an inner diameter (see arrow 68) and twosubstantially straight portions 70, 72 projecting outward fromrespective opposite ends of the bend 66. The straight portions 70, 72and have respective longitudinal lengths (see respective arrows 74, 76)that are substantially longer than the inner diameter 68. The innerconduit 56 may similarly have substantially straight portions 78, 80projecting outward from respective ends of the bend 64. These straightportion 78, 80 may have respective longitudinal lengths (see respectivearrows 82, 84) that are each longer than the inner diameter 68 of theouter conduit 58. In such a dimensional relationship, fitting of theinner conduit 56 into the outer conduit 58 may be difficult if notimpossible. Alternatively, each conduit may have multiple bends alongthe centerline 52 that may be directed in different directions, thismultiple bend configuration would also make fitting or insertion of theinner conduit 56 into the outer conduit 58 difficult, if not impossible.

The fuel injector 20 may further have a pressure release or maintenancefeature 86 supported by and communicating through the outer conduit 58for creating and maintaining the vacuum or negative atmospheric pressurein the void 60. The feature 86 may further assist in restoring thevacuum after a repair procedure or rupture of the outer conduit 58. Thefeature 86 may be additive manufactured as one unitary piece to theassembly or may be adhered and/or brazed to the outer wall 58 afteradditive manufacturing is completed. The negative atmospheric pressuremay be about three pounds per square inch (21 kPa).

The fuel injector 20 may include at least one support structure 88 forproperly locating the inner conduit 56 with respect to the outer conduit58. The support structure 88 may be generally located at one or both ofthe distal ends of the fuel injector 20 (e.g. the distal joinder of theinner conduit 56 to the outer conduit 58. Alternatively, or in additionthereto, the support structure 88 may be a plurality of pylons thattraverse the void 60 and connect the inner conduit 56 to the outerconduit 58. Such pylons are spaced axially and circumferentially withrespect to the centerline 52, may be additively manufactured as oneunitary piece to both of the conduits 56, 58, and are minimal in mass tolimit thermal conduction from the outer conduit to the inner conduit.The number of pylons are dictated by the structural needs of the fuelinjector or assembly 20 and may be about 0.004 inches (0.102millimeters) in diameter, or the minimal production capability of theadditive manufacturing process. It is further understood andcontemplated that the insulating material 61, and although looselypacked, may provide structural support in addition to (or instead of)the pylons.

The flowpath assembly 20, or portions thereof, may be additivemanufactured as one unitary and homogenous piece. Material compositionsinclude, but are not limited to, nickel (e.g. INCONEL 718, 625),Waspaloy® (of United Technologies Corporation), Stellite® (of the DeloroStellite Company), titanium, steels and stainless steels, cobalt,chrome, Hastalloy®X (of Haynes International Corporation), and others.

Referring to FIG. 3, a second embodiment of a flowpath assembly isillustrated wherein like elements have like identifying numerals exceptwith the addition of a prime symbol. The flowpath assembly 20′ of thesecond embodiment has a support structure 88′ that is generally of ahoneycomb orientation. The honeycomb may function to divide the annularvoid 60′ into a plurality of individually sealed void portions 90 eachhaving an insulating material 61′.

Referring to FIG. 4, a third embodiment of a flowpath assembly isillustrated wherein like elements have like identifying numerals exceptwith the addition of a double prime symbol. The flowpath assembly 20″ ofthe third embodiment has a support structure 88″ that is girder-like.That is, a plurality of pylons may be paired such that the ends of twopylons 92, 94 and the inner conduit 56″ connect to one-another at ajunction 96 and the opposite ends of the respective pylons 92, 94 arespaced from one-another and individually connect to the outer conduit58. In this way, minimal contact is made with the inner conduit 56″,thereby reducing thermal conduction.

Referring to FIG. 5, a fourth embodiment of a flowpath assembly isillustrated wherein like elements have like identifying numerals exceptwith the addition of a triple prime symbol. The flowpath assembly 20′″may include a third conduit 98 that co-extends with a first conduit 56′″and is surrounded by and radially spaced inward from an outer conduit58′″. All three conduits may be additive manufactured together and/orsimultaneously to simplify assembly and reduce the number of assemblyparts.

Examples of additive manufacturing processes include, but are notlimited to, laser powder bed, electron beam melting, free formfabrication laser powder deposition and electron beam wire deposition,amongst others. Additive manufacturing systems include, for example,Additive Layer Manufacturing (ALM) devices, such as Direct Metal LaserSintering (DMLS), Selective Laser Melting (SLM), Laser Beam Melting(LBM) and Electron Beam Melting (EBM) that provide for the fabricationof complex metal, alloy, polymer, ceramic and composite structures bythe freeform construction of the workpiece, layer-by-layer. Theprinciple behind additive manufacturing processes may involve theselective melting of atomized precursor powder beds by a directed energysource, producing the lithographic build-up of the workpiece. Themelting of the powder occurs in a small localized region of the energybeam, producing small volumes of melting, called melt pools, followed byrapid solidification, allowing for very precise control of thesolidification process in the layer-by-layer fabrication of theworkpiece. These devices are directed by three-dimensional geometrysolid models developed in Computer Aided Design (CAD) software systems.

One example of an additive manufacturing system 100 capable ofmanufacturing the flowpath assembly 20 is schematically illustrated inFIG. 6. The additive manufacturing system 100 has a build table 102 forsupporting the assembly 20 and generally holding a powder bed 104, aparticle spreader, wiper or sprayer 106 for spreading, spraying orotherwise placing the powder bed 104 over the manufacture portion of theassembly 20 and build table 102, an energy gun 108 for selectivelymelting regions of a layer of the powder bed, a powder supply hopper 110for supplying powder to the spreader 106, and a powder surplus hopper112. The additive manufacturing system 100 may be constructed to buildthe assembly 20, or any portions thereof, in a layer-by-layer fashion.The powder bed 104 is composed of the same material composition as theassembly being additively manufactured.

A controller 114 of the additive manufacturing system 100 may include acomputer 116 for entering data and that contains software forprogramming automated functions in accordance with inputted threedimensional computer aided design models of the assembly 20. The modelmay include a breakdown of the assembly 20 into a plurality of slices118 additively built atop one-another generally in a vertical orz-coordinate direction. Each solidified slice 118 corresponds to a layer120 of the powder bed 104 prior to solidification and each layer 120 isplaced on top of a build surface 122 of the previously solidified slice118. The controller 114 generally operates the entire system through aseries of electrical and/or digital signals 124 sent to the system 100components. For instance, the controller 114 may send a signal 124 to amechanical piston 126 of the supply hopper 110 to push a supply powder128 upward for receipt by the spreader 106. The spreader 106 may be awiper, roller or other device that pushes (see arrow 130) or otherwiseplaces the supply powder 128 over the build surface 122 of the assembly20 (or any portion thereof) by a pre-determined thickness that may beestablished through downward movement (see arrow 132) of the build table102 controlled by the controller 114. Any excess powder 128 may bepushed into the surplus hopper 112 by the spreader 106.

Once a substantially level powder layer 120 is established over thebuild surface 122, the controller 114 may send a signal 124 to theenergy gun 108 that energizes a laser or electron beam device 134 andcontrols a directional mechanism 136 of the gun 108. The directionalmechanism 136 may include a focusing lens that focuses a beam (seearrows 138) emitted from device 134 which, in-turn, may be deflected byan electromagnetic scanner or rotating mirror of the mechanism 136 sothat the energy beam 138 selectively and controllably impinges uponselected regions of the top layer 120 of the powder bed 104. The beam138 moves along the layer 120 melting region-by-regions of the layer 120at a controlled rate and power, melting each region into pools that thenform with, or sinter to, the adjacent build surface 122, solidify, andultimately form the next top slice 118. The process then repeats itselfwhere another powder layer 120 is spread over the last solidified slice118 and the energy gun 108 melts at least a portion of that layer alongwith a meltback region (i.e. sintering) of the previously solidifiedslice 118 to form a uniform and homogeneous assembly 20, or portionthereof.

The material 61 that may be loosely packed and may further haveinsulating properties may be deposited as part of the powder layer 120,and may not be melted therefore requires no solidification. The powderor granular material 61, the support structure 88, the inner conduit 56and the outer conduit 58 may all be made of the same raw powder materialwith the support structure and conduits being melted and solidified in aslice-by-slice fashion. The material 61 may be selectively bypassed bythe energy gun 108 and thus remains in its raw form. Alternatively, thematerial 61 may be deposited such that once melted it has a greaterporosity (i.e. less dense) than the surrounding conduits and supportstructure. Alternatively, the material 61 may be made of a differentmaterial than the conduits 56, 58 and possibly of a raw powder materialwith enhanced insulating and/or heat resistant properties such asceramic. Such selective deposits of differing powders may beaccomplished by processes typically known in the additive manufacturingarts. It is further anticipated and understood that the material 61 mayfunction as a structural support feature for the conduits, or may bemade of the same material composition as the structural support 88 orpylons, both having properties such that thermal conduction between theconduits is minimized.

Referring to FIG. 7, a method of additive manufacturing the flowpathassembly 20 generally includes a first step 200 of CAD modeling theflowpath assembly 20 into a plurality of slices 118. The next step 202may be additive manufacturing at least the inner and outer conduits 56,58 and possibly the support structure 88, simultaneously. A sub-portionof step 202 may include step 204 where the insulating material 61 isdeposited as part of the powder layer 120 with the exception that theregion containing the insulating material 61 is not melted by the energygun 108.

It is understood that relative positional terms such as “forward,”“aft,” “upper,” “lower,” “above,” “below,” and the like are withreference to the normal operational attitude and should not beconsidered otherwise limiting. It is also understood that like referencenumerals identify corresponding or similar elements throughout theseveral drawings. It should be understood that although a particularcomponent arrangement is disclosed in the illustrated embodiment, otherarrangements will also benefit. Although particular step sequences maybe shown, described, and claimed, it is understood that steps may beperformed in any order, separated or combined unless otherwise indicatedand will still benefit from the present disclosure.

The foregoing description is exemplary rather than defined by thelimitations described. Various non-limiting embodiments are disclosed;however, one of ordinary skill in the art would recognize that variousmodifications and variations in light of the above teachings will fallwithin the scope of the appended claims. It is therefore understood thatwithin the scope of the appended claims, the disclosure may be practicedother than as specifically described. For this reason, the appendedclaims should be studied to determine true scope and content.

What is claimed is:
 1. A flowpath assembly comprising: a fuel injectorcomprising a first conduit, a second conduit and an insulating material;the first conduit defining a flowpath radially inward and extendingalong a centerline; the second conduit spaced radially outward from thefirst conduit with a void defined by and radially between the first andsecond conduits; and the insulating material disposed in the void,wherein the void is sealed and at a negative atmospheric pressure.
 2. Aflowpath assembly comprising: a first conduit defining a flowpathradially inward and extending along a centerline; a second conduitspaced radially outward from the first conduit with a void defined byand radially between the first and second conduits; and an insulatingmaterial disposed in the void; wherein the first and second conduits areone unitary piece.
 3. A flowpath assembly comprising: a first conduitdefining a flowpath radially inward and extending along a centerline; asecond conduit spaced radially outward from the first conduit with avoid defined by and radially between the first and second conduits; aninsulating material disposed in the void; a third conduit co-extendingwith the first conduit and spaced radially inward from the secondconduit; and a support structure located in the void and engaged betweenthe first and second conduits.
 4. The flowpath assembly set forth inclaim 3, wherein the first and second conduits and the support structureare additive manufactured as one unitary piece.
 5. The flowpath assemblyset forth in claim 4, wherein the insulating material has a greaterporosity than the conduits.
 6. The flowpath assembly set forth in claim1, wherein the first conduit is substantially concentric to the secondconduit.
 7. A flowpath assembly comprising: a first conduit for flowinga fluid; a second conduit surrounding and spaced radially outward fromthe first conduit with an insulating void defined between the first andsecond conduits; a loosely packed material in the void; and wherein theflowpath assembly is additive manufactured as one unitary piece.
 8. Theflowpath assembly set forth in claim 7, wherein the material hasinsulating properties and is deposited during additive manufacturing ofthe first and second conduits.
 9. The flowpath assembly set forth inclaim 7 comprising: a support structure in the void and including aplurality of pylons each engaged to and extending between the first andsecond conduits.
 10. The flowpath assembly set forth in claim 9, whereinthe insulating material and the support structure have the same materialcomposition.
 11. The flowpath assembly of claim 1, wherein a portion ofthe first conduit bends as the first conduit extends along thecenterline.
 12. The flowpath assembly of claim 1, wherein the firstconduit extends to a nozzle orifice of the fuel injector, and a diameterof the nozzle orifice is less than a diameter of the first conduit. 13.A flowpath assembly comprising: a fuel injector comprising a firstconduit, a second conduit and an insulating material; the first conduitdefining a flowpath radially inward and extending along a centerline;the second conduit spaced radially outward from the first conduit with avoid defined by and radially between the first and second conduits; andthe insulating material disposed in the void, wherein the first andsecond conduits are additive manufactured simultaneously, and whereinthe insulating material is a powder deposited during the simultaneousadditive manufacturing of the first and second conduits.